The Red Sox designated McGuire for assignment Sunday, Rob Bradford of WEEI.com reports.
The 29-year-old will be bumped off the 26-man active roster and 40-man roster to make room for trade acquisition Danny Jansen, who will replace McGuire as Boston's new No. 2 catcher. McGuire posted a .209/.280/.295 slash line with three home runs in 52 games for the Red Sox this season.